1. Field Of The Invention
The present invention relates to a method of manufacturing integrated circuits and other electronic devices. More particularly, the invention relates to an improved process for the forming and etching of titanium containing film on a semiconductor wafer.
2. Description Of The Related Art
Interconnect technology is increasingly a major limitation in the fabrication of very large scale integrated circuits. In the past, the various methods have been utilized to interconnect different portions of integrated circuits. Another and more efficient method for forming interconnects has been developed. This method forms what are called local interconnects.
A local interconnect generally refers to an interconnection that provides direct local connections between the source and drain junctions at the interconnect level and the gate interconnect level, without the use of additional contacts and metal straps.
U.S. Pat. No. 4,675,073 ('073), owned by a common assignee and incorporated by reference, discloses a method for forming titanium nitride local interconnects using a well known plasma etch process. One local interconnect structure, disclosed in '073, is formed from a layer of titanium nitride that is in direct contact with the exposed gate electrode material after the gate level of interconnect has been defined and etched. Another local interconnect structure, as disclosed in '073, can be formed from a layer of titanium nitride that connects the source or drain of a first transistor to the source or drain of a second transistor. In either case, however, the local interconnect layer cannot be the same material as the gate electrode or the gate level of interconnect because the etch process required to define the local interconnects must have high selectivity to the gate and junction interconnect materials. If it does not, these interconnections may be seriously degraded during the local interconnect etching step. Thus, the forming and etching processes for local interconnects must be highly selective in order to efficiently manufacture devices using local interconnects.
U.S. patent application Ser. No. 074,377 filed Jul. 16, 1987, incorporated by reference, discloses an advanced vacuum processor. Such a process can be used to etch or deposit various materials. It utilizes both a remotely generated plasma and a plasma generated in the process chamber whose feed gas is the discharge of the remote plasma generator. In this way, it is able to achieve a synergistic combination of etchant power sources for various materials, thereby, obtaining higher etch rates with more control over both anisotropy and selectivity.